Method for controlling the molecular weight during poly(arylene vinylene) synthesis, and polymers produced therewith

ABSTRACT

The present invention relates to a process in which addition of certain bis(methyl)aryl compounds which have a further substituent other than hydrogen and on which at least one of the two methyl groups bears a leaving group, the molecular weight in the synthesis of poly(arylenevinylenes) is controlled reproducibly and can be deduced by the GILCH polymerization or by the sulfinyl precursor route, and to the polymers obtainable by means of the process according to the invention.

RELATED APPLICATIONS

This application is a national stage application (under 35 U.S.C. 371)of PCT/EP2004/003860 filed Apr. 13, 2004 which claims benefit to Germanapplication 103 18 096.6 filed Apr. 17, 2003.

For about 12 years, broad-based research has proceeded into thecommercialization of display and illumination elements based onpolymeric (organic) light-emitting diodes (PLEDs). This development wastriggered by the fundamental developments which are disclosed in EP 423283 (WO 90/13148). The only polymers which currently satisfy the marketdemands in relation to efficiency and lifetime are based onpoly-(arylenevinylenes). Recently, a first product in the form of arelatively small display has also become available on the market in anelectric shaver from Philips N.V. which contains a polymer of thisclass. However, distinct improvements are still needed in order to makethese displays a real competitor to the currently market-leadingliquid-crystal displays (LCD).

EP 423 283 and EP 443 861 describe, as polymeric materials for thelight-emitting layer, poly(p-phenylenevinylenes) which have beenmodified on the aromatic ring with alkyl, alkoxy, halogen or nitrosubstituents to improve the properties. Such polymers have since thenbeen investigated in a large number of studies.

WO 98/27136 describes aryl-substituted poly(p-arylene-vinylenes) whichare also suitable for generating green electroluminescence. A furtherimprovement in the polymers described there is disclosed in WO 99/24526.Here, a defect in such polymers is also disclosed: depending on thepolymer, varying fractions of triple and single bonds occur in the mainchain instead of the double bond (TBB defect). The fraction of thisdefect is apparently in a reciprocal relationship to the achievablelifetime: a high defect fraction reduces the operative lifetime; a lowfraction increases it significantly. The application WO 99/24526mentioned discloses that the defect rate can be influenced by thesubstitution pattern used, and that this rate can be distinctly reducedstarting from aryl-substituted monomers (according to WO 98/27136) bythe introduction of CN, F, Cl, an amino, alkyl or (thio)alkoxy group.

WO 01/34722 (EP 1232225) disclosed that poly-(arylenevinylenes) whichcontain monomer units whose phenylene unit bears a further arylsubstituent para or meta to a first aryl radical have this effectoutlined in the abovementioned application to an unexpectedly markedextent. This allows the operative lifetime in EL elements to beincreased even further. This is of course of great relevance to theapplication and economic significance. The high EL efficiencies areretained.

U.S. Pat. No. 5,558,904 discloses polymers analogously to thosespecified above, in which the two substituents are either unsubstitutedor substituted only by short-chain substituents (fluorine, cyano,methoxy, phenyl). Homo-polymers or else copolymers having a fraction ofsuch structures of greater than approx. 25 mol % are, however, found tobe insoluble.

In the context of this application, solubility and insolubility will bedefined as is also specified in WO 99/21936 (page 3, lines 2 to 7): theterm “soluble polymer” thus means that it forms a clear, ungelledsolution at room temperature or at least at a temperature below 60° C.,preferably below 50° C., more preferably below 40° C., in theconcentration range of at least 0.5% by weight in a common organicsolvent (aromatic, and also nonaromatic solvents which may containhalogen atoms or else may be halogen-free, for example toluene, anisole,chlorobenzene, methylene chloride, chloroform, xylenes, dioxane, THF,cyclohexanone, and the like). This property is necessary in order to beable to ensure industrial processing to give thin films. In the sense ofthis definition, insoluble polymers are, in contrast, those which giverise to a clear solution only at distinctly lower concentrations orwhich gel even above approx. 60° C.

A particularly suitable synthesis method for poly-(arylenevinylenes) iswhat is known as GILCH polymerization which leads, starting from1,4-bis(halomethyl)benzene which is substituted by solubility-promotinggroups, in a base-induced manner to the desired soluble polymers (H. G.Gilch et al., J. Polym. Sci.: A-1 1966, 4, 1337). Thepoly-(phenylenehaloethylenes) formed as intermediates are converteddirectly by the base excess used to the conjugatedpoly(arylenevinylenes). An optimization of this method, as disclosed inWO 99/24526 and WO 98/27136, led already to polymers with a very lowdefect rate and increased the reproducibility of the synthesis.Reference is made here explicitly to the texts of these applications,and they are thus part of the present application by reference.

A further suitable synthesis method is the sulfinyl precursor route, thebase-induced polymerization of 1-halomethyl-4-(sulfinylmethyl)arylenes.This is described, for example, in EP 644217 and EP 705857 and in thepublication of A. J. J. M. van Breemen et al. (Macro-molecules 1999, 32,5728-5735). The initially isolated poly(phenylenesulfinylethylene)polymers are converted in a second step thermally to the conjugatedpoly(arylenevinylenes). This method is part of the present applicationby reference.

As already indicated above, it is, however, frequently difficult forboth methods to find monomers with suitable substituents which, on theone hand, lead to soluble polymers but, on the other hand, also have thedesired electronic and/or positive polymerization properties.

There is currently an emerging development in the fabrication ofdisplays based on light-emitting polymers, which is increasingly movingaway from the common processes for surface coatings, for example byspincoating processes or knifecoating techniques, in favor of newspatially resolved printing processes in the widest sense, for exampleinkjet printing, offset printing, screenprinting processes, gravureprinting and the like. For this purpose, it is necessary firstly to beable to vary the concentration of the polymer solution within a widerange and adjust it very precisely in order to obtain the desired layerthickness in the printing. For this purpose too, it is thus becomingincreasingly important to have available highly soluble polymers.Secondly, it is likewise essential for these techniques to preciselyadjust the viscosity of the solution in order to be able to optimize theprinting properties for the appropriate printing process. Since theviscosity of a polymer solution is approximately proportional to themolecular weight of the polymer cubed, it is apparent that precise andreproducible control of the molecular weight is required for thispurpose in particular. For example, US 2001/0003602 states that amolecular weight M_(w)<600 kDa, preferably in the range from 20 to 100kDa, is required for inkjet printing of poly(arylenevinylenes). For thispurpose, WO 02/096970 specifies a preferred molecular weight range ofM_(n)<300 kDa and M_(w)<500 kDa.

For this reason, it is desirable to have available a method formolecular weight control of the polymers, in order to obtain readilysoluble polymers reproducibly with a multitude of differentsubstituents, which can be used not only for surface coatings, but alsofor printing processes.

U.S. Pat. No. 5,817,430 describes the synthesis ofpoly-(arylenevinylenes) to which compounds R—H are added in thepolymerization process and control the chain ends, R—H being a compoundwhich contains at least one acidic proton, and R being a nucleophile. Ris then intended to form the end groups of the polymer. Reduction of themolecular weight thus affords soluble polymers. In the subsequentpublications of Hsieh et al. (Macromolecules 1997, 30, 8094-8095; J. Am.Chem. Soc. 1998, 120, 231-232) and of Ferraris et al. (Macromolecules2000, 33, 2311), this method is described in detail: the reduction inthe molecular weight is achieved by a modification of the GILCHpolymerization, by the addition to the reaction mixture ofnonpolymerizable acidic additives, for example 4-tert-butylbenzylchloride, 4-tert-butylbenzyl bromide or 4-methoxyphenol. The molecularweight can then purportedly be controlled by variation of the ratiobetween the monomers and the nonpolymerizable additive. However,in-house experiments indicate that the addition of such additives, asproposed in U.S. Pat. No. 5,817,430, by Hsieh et al. and by Ferraris etal., does not have any significant influence on the molecular weight ofthe polymer. Subsequently, the results have likewise been contradictedin a publication by Vanderzande et al. (Belg. Polymer 2001, 42,5793-5796), which showed that the additives do not exhibit the reportedeffect and that they barely reduce the molecular weight, or that theaddition of these compounds leads to poorly reproducible polymerizationresults. These results are thus irreproducible even to those skilled inthe art, so that there exists no prior art method of controlling and ofreducing the molecular weight of poly(arylenevinylenes) in the GILCHpolymerization or in-the sulfinyl precursor route.

Another method of obtaining homogeneous solutions which can be filteredwithout any problem from sparingly soluble or nonfilterablepoly(arylenevinylenes) is illustrated in WO 03/019694. There, a crudesolution is treated by mechanical processes (for example by ultrasoundor by the use of high-shear dispersing stirrers). This results incomminution of the chemical or physical aggregates of the polymer chainsand thus reduction in the molecular weight. This method can be used veryadvantageously in order to balance relatively small charge variations inthe synthesis and to achieve a reproducible concentration-viscosityratio. In addition, this process can also be used for controlledenhanced molecular weight degradation. However, the use of ultrasound,especially when the polymer solution is exposed to the ultrasound for aprolonged period, also has a negative influence on the performance ofthe polymer when used in PLEDs, so that this does constitute a means ofmaking processible poly(arylenevinylenes) which would otherwise not beprocessible, but a more gentle solution for molecular weight controlwould be desirable in the long term.

There is thus still a great need for a process which enables themolecular weight of poly(arylenevinylenes) in the GILCH polymerizationand in the sulfinyl precursor polymerization to be controlled and to bereduced in order to make obtainable other structures which wouldotherwise have led to insoluble material, and in order to adjust theproperties of this important material class also to modern printingtechniques.

It has now been found that, surprisingly, the addition of certainsubstituted bismethylaryl compounds which bear a leaving group, forexample a halogen atom or a trifluoro-methanesulfonate group, on atleast one of the two methyl groups, and also, on each of the two methylgroups, a further substituent other than hydrogen to the polymerizationprocess enables the molecular weight of poly-(arylenevinylenes) in theGILCH polymerization and in the sulfinyl precursor polymerization to becontrolled and to be reduced effectively and reproducibly. At the sametime, the properties of the polymers when used in PLEDs (efficiency,lifetime) remain unchanged and good.

The invention thus provides a process for the base-induced preparationof poly(arylenevinylenes) from bis(halomethyl)-arylenes or fromhalomethylsulfinylmethylarylenes, characterized in that the reaction iscarried out in the presence of 0.1-80 mol %, preferably 0.5-60 mol %,more preferably 1-50 mol %, in particular 2-40 mol %, of one or morecompounds of the formula (I):

where the symbols are defined as follows:

-   Aryl is the same or different at each instance and is a bivalent    aromatic or heteroaromatic ring system which has from 2 to 40 carbon    atoms and may be substituted by R¹ radicals or else be    unsubstituted, or an R¹-substituted or unsubstituted stilbenylene    unit; the two substituents CHXR and CHYR are arranged in such a way    that there is an even number of aromatic atoms between them; the    aryl and heteroaryl systems may also be part of a larger fused    aromatic ring system; the possible substituents R¹ may potentially    be situated at any free position;-   R is the same or different at each instance and is an alkyl chain    which has from 1 to 40 carbon atoms and may be straight-chain,    branched or cyclic, and may also be substituted by one or more R¹    radicals or be unsubstituted, in which one or more nonadjacent    carbon atoms may also be replaced by —CR²═CR²—, —C≡C—, —NR²—, —O—,    —S—, —CO—, —CO—O—, —CONR²—, —O—CO—O—, and one or more hydrogen atoms    may also be replaced by fluorine, an aromatic or heteroaromatic ring    system which has from 2 to 40 carbon atoms and may be substituted by    R¹ or be unsubstituted, an R¹-substituted or unsubstituted stilbenyl    or tolanyl unit, —Si(R²)₃, —N(R²)₂, —OR² or a combination of these    systems; the aryl and heteroaryl systems may also be part of a    larger fused aromatic ring system; the possible substituents may    potentially be situated at any free position;-   X is the same or different at each instance and is Cl, Br, I,    trifluoromethanesulfonate or arylsulfonate;-   Y is the same or different at each instance and is Cl, Br, I,    trifluoromethanesulfonate, arylsulfonate, —S(O)—R² or R¹;-   R¹ is the same or different at each instance and is a    straight-chain, branched or cyclic alkyl chain having from 1 to 40    carbon atoms, in which one or more non-adjacent carbon atoms may    also be replaced by —CR²═CR²—, —C≡C—, —NR²—, —O—, —S—, —CO—, —CO—O—,    —CONR²—, —O—CO—O—, and one or more hydrogen atoms may be replaced by    fluorine, an aromatic or heteroaromatic ring system which has from 2    to 40 carbon atoms and may also be substituted by one or more    nonaromatic R¹ radicals, a substituted or unsubstituted vinyl group    or Cl, F, CN, N(R²)₂, B(R²)₂ or a combination of these systems; the    aryl and heteroaryl systems may also be part of a larger fused    aromatic ring system; the possible substituents may potentially be    situated at any free position; two or more R¹ radicals together may    also form a ring system;-   R² is the same or different at each instance and is H, a    straight-chain, branched or cyclic alkyl chain having 1 to 22 carbon    atoms, in which one or more nonadjacent carbon atoms may also be    replaced by —O—, —S—, —CO—O—, —O—CO—O—, and one or more hydrogen    atoms may also be replaced by fluorine, an aryl or heteroaryl system    which has from 2 to 40 carbon atoms and may also be substituted by    one or more nonaromatic R¹.

The monomers are preferably compounds of the formula (XXVI)

where aryl, R¹ and R² are each defined as described under formula (I)and the further symbols used are:

-   X is the same or different at each instance and is Cl, Br, I,    trifluoromethanesulfonate or arylsulfonate;-   Z is the same or different at each instance and is Cl, Br, I,    trifluoromethanesulfonate, arylsulfonate or —S(O)R².

For the GILCH process, X and Z are preferably each Cl, Br or I. For thesulfinyl precursor process, X is preferably Cl, Br or I and Z is—S(O)R².

For the GILCH process, the monomers, i.e. 1,4-bis-(halomethyl)arylcompounds, are dissolved in the desired ratio relative to one another ina suitable concentration in a suitable solvent with addition of asuitable amount of compound of the formula (I), brought to a suitablereaction temperature and admixed with a suitable base. After a suitablereaction time has elapsed, the reaction can be terminated, for exampleby acid addition. Subsequently, the polymer is purified by suitableprocesses familiar to those skilled in the art, for examplereprecipitation or extraction. Suitable solvents are, for example,ethers (e.g. diethyl ether, THF, dioxane, dioxolane, tert-butyl methylether), aromatic hydrocarbons (e.g. toluene, xylenes, anisole,methylnaphthalene), chlorinated compounds (e.g. chlorobenzene,dichlorobenzene) or mixtures of these solvents.

A suitable concentration range is the interval from 0.005 to 5 mol/l(monomer/solution volume). The range is preferably from 0.01 to 2 mol/l,more preferably from 0.01. to 0.5 mol/l.

The reaction temperature is generally between −80 to 200° C., preferablybetween 20 and 140° C.

Suitable bases are, for example, alkali metal hydroxides (e.g. NaOH,KOH), alkali metal hydrides (e.g. NaH, KH), alkali metal alkoxides (e.g.NaOEt, KOEt, NaOMe, KOMe, KO^(t)Bu), metal organyls (e.g. MeLi,^(n)BuLi, ^(s)BuLi, ^(t)BuLi, PhLi) and organic amines and amides (e.g.LDA, DBU, DMAP, pyridine).

A suitable amount of base is in the range from 2 to 10 equivalents ofbase (based on one equivalent of monomer), preferably from 3.5 to 8equivalents of base, more preferably from 4 to 6 equivalents of base.

The reaction time is generally between 5 minutes and 72 h, preferablybetween 0.5 and 24 h, more preferably between 1 and 6 h.

The addition of compound of the formula (I) for molecular weight controlis between 0.1 and 80 mol % (based on the total amount of the othermonomers), preferably between 0.5 and 60 mol %, more preferably between1 and 50 mol %, in particular between 2 and 40 mol %, and is selecteddepending on the desired molecular weight of the polymer.

For the sulfinyl precursor route, the monomers, i.e.1-halomethyl-4-sulfinylmethylaryl compounds, are dissolved in thedesired ratio relative to one another in suitable concentration in asuitable solvent with addition of a suitable amount of compound of theformula (I), brought to a suitable reaction temperature and admixed witha suitable amount of base. After a suitable reaction time has elapsed,the reaction can be terminated, for example by acid addition.Subsequently, the precursor polymer is purified by suitable processesknown to those skilled in the art, for example reprecipitation orextraction. The poly(arylenevinylene) compound is then obtained bythermal action on the polymer under suitable conditions, in solution orin a film.

Suitable solvents are, for example, ethers (e.g. diethyl ether, THF,dioxane, dioxolane, tert-butyl methyl ether), aromatic hydrocarbons(e.g. toluene, xylenes, anisole, methylnaphthalene), chlorinatedcompounds (e.g. chloro-benzene, dichlorobenzene, dichloromethane), butalso DMSO or protic solvents (e.g. MeOH, EtOH, ^(n)PrOH, ^(n)BuOH,^(n)PeOH, ^(i)PrOH, ^(s)BuOH, ^(s)PeOH, ^(tert)BuOH) or mixtures ofthese solvents.

A suitable concentration range is the interval from 0.005 to 5 mol/l(monomer/solution volume). The range is preferably from 0.01 to 2 mol/l,more preferably from 0.01 to 0.5 mol/l.

The reaction temperature is generally between −80 to 200° C., preferablybetween 0 and 120° C.

Suitable bases are, for example, alkali metal hydroxides (e.g. NaOH,KOH), alkali metal alkoxides (e.g. NaOEt, KOEt, NaOMe, KOMe, KO^(t)Bu)and organic amines and amides (e.g. LDA, DBU, DMAP, pyridine), but alsoalkali metal hydrides (e.g. NaH, KH) where nonprotic solvents are used,or metal organyls (e.g. MeLi, ^(n)BuLi, ^(s)BuLi, ^(t)BuLi, PhLi) whennonprotic solvents and not DMSO are used.

A suitable amount is in the range from 1 to 20 equivalents of base(based on one equivalent of monomer), preferably from 1 to 10equivalents of base, more preferably from 1 to 5 equivalents of base.

The reaction time is generally between 5 minutes and 72 h, preferablybetween 0.5 and 6 h, most preferably between 1 and 4 h.

The addition of compounds of the formula (I) for molecular weightcontrol is between 0.1 and 80 mol % (based on the total amount of theremaining monomers), preferably between 0.5 and 60 mol %, morepreferably between 1 and 50 mol %, in particular between 2 and 40 mol %,and is selected depending on the desired molecular weight of thepolymer.

The poly(aryleneethylene) precursor polymer is converted to theconjugated poly(arylenevinylene) by thermal treatment. A suitabletemperature therefor is from 50 to 250° C., preferably from 80 to 200°C., more preferably from 100 to 150° C., and the conversion may becarried out either in solution or in a film.

Preference is given to selecting compounds of the formula (I) in whichthe symbols are:

-   Aryl is the same or different at each instance and is a bivalent    aromatic ring system which has from 2 to 40 carbon atoms and may be    substituted by up to 4 substituents R¹ or else be unsubstituted, or    an R¹-substituted or unsubstituted stilbenylene unit; the two    substituents CHXR and CHYR are arranged in such a way that there is    an even number of aromatic atoms between them; the aryl system may    also be part of a larger fused aromatic ring system; the possible    substituents R¹ may potentially be situated at any free position;-   R is as defined above;-   X is the same or different at each instance and is Cl, Br, I;-   Y is as defined above;-   R¹, R² are each as defined above.

Particular preference is given in this context to compounds of theformula (I) for which:

-   Aryl is the same or different and is a bivalent aromatic ring system    which has from 2 to. 20 carbon atoms and may be substituted by from    0 to 4 substituents R¹ or else be unsubstituted, or an    R¹-substituted or unsubstituted stilbenylene unit; the two    substituents CHXR and CHYR are arranged in such a way that the    number of aromatic atoms of the aryl unit between them is a multiple    of 4; the aryl system may also be part of a larger fused aromatic    ring system; the possible substituents R¹ may potentially be    situated at any free position;-   R is the same or different at each instance and is an alkyl chain    having from 1 to 20 carbon atoms, in which the carbon atom with    which it, is joined to the CHX group or CHY group does not bear any    hydrogen atoms and which may otherwise be straight-chain, branched    or cyclic and may also be substituted by R¹ or be unsubstituted, in    which one or more nonadjacent carbon atoms may also be replaced by    —CR²═CR²—, —C≡C—, —NR²—, —O—, —S—, —CO—, —CO—O—, —CONR²—, —O—CO—C—,    and one or more hydrogen atoms may also be replaced by fluorine, an    aromatic or heteroaromatic ring system which has from 2 to 20 carbon    atoms and may also be substituted by one or more nonaromatic R¹    groups, or —Si(R³)₃, —N(R²)₂, —OR²; the aryl and heteroaryl systems    may also be part of a larger fused aromatic ring system; the    possible substituents may potentially be situated at any free    position;-   X is the same or different at each instance and is Cl or Br;-   Y is the same or different at each instance and is Cl, Br or    —S(O)R²;-   R¹, R² are each as defined above.

Some particularly preferred compounds of the formula (I) are theformulae (II) to (XXV) depicted below, possible substituents usually notbeing depicted for the sake of clarity:

The compound of the formula (I) is incorporated into thepoly(arylenevinylene) formed in the polymerization. It may beincorporated into the polymer chain or as a polymer chain end group.

In order to investigate which fraction is actually incorporated andwhether the incorporation takes place only at the chain ends or elsewithin the chain, a molecule was synthesized which is substituted on thearomatic R radicals with one CF₃ group in each case (see Example 3:IA3). This compound was added to a polymerization (see Example 8:polymer P4), and the resulting polymer was analyzed by ¹⁹F NMRspectroscopy. By addition of trifluorotoluene as an internal standardand integration over the signals, it was possible to show that theadditive is also incorporated into the chain and not only at the chainends, since the fluorine content of the polymer was higher than expectedfor a polymer that would contain the additive only at the chain ends.

Poly(arylenevinylenes) which are prepared by base-induced polymerizationof bis(halomethyl)arylene or from halomethyl-sulfinylmethylarylene inthe presence of 0.1-80 mol %, preferably 0.5-60 mol %, more preferably1-50 mol %, in particular 2-40 mol %, of compounds of the formula (I)are likewise novel and inventive. As a result of the incorporation ofthe compound of the formula (I) into the polymer main chain or as apolymer end group, these units of the formula (I) are present in the endproduct.

The invention thus likewise provides poly(arylenevinylenes) containingat least 0.1 mol % of units of the formula (Ia) and/or (Ib)

where aryl, R, X, Y, R¹ and R² are each defined as described above underformula (I), and

-   poly represents a bond to a poly(arylenevinylene) main chain.

The poly(arylenevinylenes) prepared by means of the process according tothe invention exhibit comparable or improved electronic properties, suchas lifetime and efficiency, but have distinctly better solubility thanpoly-(arylenevinylenes) according to the prior art.

The thus obtained poly(arylenevinylenes) can be used in PLEDs. To thisend, the following general process is generally used, which is to beadapted correspondingly to the individual case:

-   -   A substrate (for example glass or else a plastic such as        specially treated PET) is coated with a transparent anode        material (for example indium tin oxide, ITO); subsequently, the        anode is structured according to the desired application (for        example photolithographically) and connected in a circuit. It is        also possible here for the whole substrate and the corresponding        circuit first to be obtained by a quite complicated process in        order thus to enable what is known as active matrix control.    -   Subsequently, either over the full surface or only at the active        (=anodic) sites, a conductive polymer, for example a doped        polythiophene or polyaniline derivative, is generally applied        first. This is generally done by coating processes which apply a        dispersion of the corresponding polymer. Suitable for this        purpose are in principle the processes described below for the        light-emitting polymer. The layer thickness of this polymer        intermediate layer may vary within wide ranges, but for        practical application will be in the range between 10 and 1000        nm, preferably between 20 and 500 nm.    -   To this is then applied a solution of a poly-(arylenevinylene)        which has been obtained by the process according to the        invention. For multicolor display elements (displays), a        plurality of different solutions are then applied in different        regions in order to obtain corresponding colors. To this end,        the poly-(arylenevinylenes) are first dissolved in a suitable        solvent or solvent mixture and then filtered. Since the organic        polymers and in particular the intermediate layers (interfaces)        in the PLED are in some cases influenced to an extreme extent by        oxygen or other air constituents, it is advisable to carry out        this operation under protective gas. Suitable solvents are        aromatic solvents, for example toluene, xylenes, anisole,        chlorobenzene, but also others, for example cyclic ethers (e.g.        dioxane, methyldioxane) or else amides (e.g. NMP or DMF), but        also solvent mixtures as described in the application document        WO 02/072714.

These solutions can be used to coat the above-described carriers, eitherover the whole surface, for example by spincoating processes orknifecoating techniques, or else in a spatially resolved manner byprinting processes in the widest sense, such as inkjet printing, offsetprinting, screenprinting processes, gravure printing processes and thelike.

-   -   To these layers may optionally be applied further electron        injection materials, for example by vapor deposition, or else        from solution by methods as have been described for the emitting        compounds. The electron injection materials used may, for        example, be low molecular weight compounds such as triarylborane        compounds or else aluminum trishydroxyquinolinate (Alq₃), but        also corresponding polymers, for example poly-pyridine        derivatives and the like. It is also possible to convert thin        layers of the emitting compound by appropriate doping to        electron injection layers.    -   Thereafter, a cathode is applied by vapor deposition. This is        generally done by a vacuum process and may be accomplished, for        example, either by thermal vapor deposition or by plasma        spraying (sputtering). The cathode may be applied over the full        surface or else structured through a mask. The cathodes used are        generally metals having a low work function, for example alkali        metals, alkaline earth metals and f transition metals, for        example Li, Ca, Mg, Sr, Ba, Yb, Sm or aluminum, or else alloys        of metals or multilayer structures comprising different metals.        In the latter case, it is also possible to use metals which have        a relatively high work function, for example Ag. It may also be        preferred to introduce a very thin dielectric layer. (for        example LiF, BaF₂ or the like) between the metal and the        emitting polymer or the electron injection layer. The cathodes        are generally between 10 and 10000 nm thick, preferably between        20 and 1000 nm thick.    -   Subsequently, the thus obtained PLEDs or displays are        appropriately connected and encapsulated in order then to be        tested or used.

The polymers synthesized by the process according to the invention areoutstandingly suitable for use as electroluminescent materials sincethey have better solubility than analogous polymers which have beensynthesized by conventional processes. As a result, they are, forexample, more readily filterable in processing and form more homogeneouspolymer films. Moreover, this process makes possible the synthesis ofnovel polymers or novel monomer combinations which lead to insolublegels by conventional processes. The processing of the thus obtainedpolymers by various printing techniques is also distinctly improved overconventionally synthesized polymers.

Just like polymers which have been synthesized by conventionalprocesses, the polymers obtained by the process according to theinvention have comparatively high efficiencies and lifetimes inoperation in PLEDs. Although this is not a direct advantage over theknown polymers, it is essential for application that these propertiesare also retained in the process according to the invention.

Electroluminescent materials in the context of the invention areregarded as being materials which find use as an active layer in anelectroluminescent device. Active layer means that the layer is capable,on application of an electric field, of emitting light (light-emittinglayer) and/or that it improves the injection and/or the transport of thepositive and/or negative charges (charge injection or charge transportlayer).

The general structure of such electroluminescent devices is described,for example, in U.S. Pat. Nos. 4,539,507 and 5,151,629.Electroluminescent devices comprising polymers are described, forexample, in WO 90/13148 or EP 0 443 861.

The invention likewise provides for the use of polymers which have beenobtained by the process according to the invention in an electronicdevice, in particular as an electroluminescent material inelectroluminescent devices. However, it is also possible for thoseskilled in the art without any further inventive activity also toutilize these polymers for other applications, for example in organicintegrated circuits (O-ICs), in organic field-effect transistors(OFETs), in organic thin-film transistors (OTFTs), in organic solarcells (O-SCs), in nonlinear optics or else in organic laser diodes(O-laser), to name just a few possible applications.

The invention therefore further provides electronic devices, for exampleorganic integrated circuits (O-ICs), organic field-effect transistors(OFETs), organic thin-film transistors (OTFTs), organic solar cells(O-SCs), organic photorefractive elements, nonlinear optics or organiclaser diodes (O-laser), but in particular polymeric light-emittingdiodes (PLEDs) comprising at least one inventive polymer.

The invention is illustrated in detail by the examples which followwithout any intention thus to restrict it.

EXAMPLES

Synthesis of inventive additives (IA) of the formula (I) The identity ofthe compounds was proved by ¹H NMR spectroscopy; the purity was checkedby HPLC measurements.

Example 1 Synthesis of IA1

In this structure, C₁₀ is a 3,7-dimethyloctyl group.2,5-Bis-(chloromethyl)-1-(3,7-dimethyloctyloxy)-4-methoxybenzene wassynthesized according to the literature (H. Becker et al.,Macromolecules 1999, 32, 4925-4932).

Synthesis of2,5-bis(acetoxymethyl)-1-(3,7-diethyloctyloxy)-4-methoxybenzene

A 4 l four-neck flask with condenser, internal thermometer and magneticstirrer was initially charged under nitrogen with 324.6 g (0.95 mol) of2,5-bis(chloromethyl)-1-(3,7-dimethyloctyloxy)-4-methoxybenzene whichwere admixed with 233.3 g (2.85 mol) of sodium acetate, 145.5 g (1.43mol) of acetic anhydride and 2000 ml of glacial acetic acid. The whitesuspension was heated to 90° C. Initially, a clear solution formed, thena white precipitate. After 2 h at 90° C., 1500 ml of acetic acid wereremoved on a rotary evaporator. The residue was admixed with 1500 ml ofwater. The waxy product which was obtained was dissolved by adding 1000ml of hexane. The phases were separated and the aqueous phase wasextracted with 2×300 ml of hexane. The combined organic phases werewashed with 1×500 ml of water and dried over Na₂SO₄, and the solvent wasremoved under reduced pressure. 370 g (96% of theory) of a yellow oilwere obtained, which became a waxy solid in a refrigerator. The crudeproduct was used directly for the next stage without furtherpurification or characterization.

Synthesis of2,5-bis(hydroxymethyl)-1-(3,7-dimethyloctyl-oxy)-4-methoxybenzene

In a 3 l four-neck flask with condenser and precision glass stirrer,144.9 g (3.62 mol) of sodium hydroxide were dissolved in 1800 ml ofethanol. After addition of 370 g (0.91 mol) of2,5-bis(acetoxymethyl)-1-(3,7-dimethyloctyl-oxy)-4-methylbenzene, themixture was stirred at room temperature for 3 h and at 45° C. for 2.5 h.The mixture was poured onto 2000 ml of water, and the solid which formedwas filtered, stirred 3 times with water and filtered again. From themother liquor, a second fraction was obtained which was likewise stirred3× with water. The two combined fractions were stirred with hexane atroom temperature for 0.5 h, filtered and dried. 183.8 g of white powderwere obtained, which were used without further workup and withoutfurther characterization directly in the next stage.

Synthesis of 2-(3,7-dimethyloctyloxy)-5-methoxyterephthal-aldehyde

A 4 l four-neck flask with condenser, precision glass stirrer, internalthermometer and dropping funnel was initially charged with 176.8 g (1.39mol) of oxalyl chloride and 450 ml of dichloromethane and cooled to −50°C. To this was added dropwise within 45 min a solution of 253.5 g (3.43mol) of DMSO in 450 ml of dichloromethane. The mixture was stirred for afurther 30 min. A solution of 183.8 g (0.57 mol) of2,5-bis(hydroxymethyl)-1-(3,7-dimethyloctyl-oxy)-4-methoxybenzene in 500ml of dichloromethane was then added dropwise over 2.5 h. After additionof 100 ml, a white precipitate formed. After addition of 400 ml of thesolution, a further 500 ml of dichloromethane were added. After theaddition had been completed, the mixture was stirred for a further 15min, then 151.8 g (1.5 mol) of triethylamine were added dropwise within1 h. The mixture was allowed to come to room temperature overnight, then1500 ml of water were added and the mixture was stirred for 0.5 h. Thephases were separated, and the aqueous phase was extracted with 2×300 mlof water. The combined organic phases were washed with 1×500 ml of waterand dried over Na₂SO₄, and the solvent was removed under reducedpressure. 175.6 g (58% of theory) of the product were obtained, whichwas used for the next stage without further purification and withoutfurther characterization.

2,5-Bis(phenylhydroxymethyl)-1-(3,7-dimethyloctyloxy)-4-methoxybenzene

A 6 l four-neck flask with precision glass stirrer, reflux condenser and2 dropping funnels was initially charged with 26.7 g (1.1 mol) ofmagnesium turnings. The apparatus was baked out under argon. At roomtemperature, 10 ml of absolute THF and a few crystals of iodine wereadded and the mixture was stirred briefly. Subsequently, a few ml ofbromobenzene were added dropwise to the unstirred solution, and at thepoint of dropwise addition was heated briefly with a hot air blower.After the start of the reaction, a total (including the amount alreadyadded) of 215 g (1.37 mol) of bromobenzene were added dropwise within 45min. At the same time, 490 ml of absolute THF were added. After thedropwise addition, the mixture was stirred under reflux for 1.5 h.Subsequently, a solution of 175.6 g (0.55 mol) of2-(3,7-dimethyloctyloxy)-5-methoxyterephthalaldehyde in 600 ml ofabsolute THF were added dropwise with ice cooling. After half of theaddition, the gel which had formed was admixed with 3000 ml of distilledtoluene and dissolved with heating to 70° C. After cooling to roomtemperature, the remaining solution of terephthalaldehyde was addeddropwise, and the viscous solution was stirred at 70° C. for a further 4h. The reaction mixture was stirred into 4000 ml of ice-water with 40 mlof conc. H₂SO₄. The phases were separated and the aqueous phase wasextracted with 1×500 ml of ethyl acetate. The combined organic phaseswere washed with 1×300 ml of water and dried over Na₂SO₄, and thesolvent was removed under reduced pressure. The crude product wasstirred with n-hexane twice at room temperature and once at 50° C., andfiltered. Further purification was effected by melting the crude productat 65° C. in hexane. This operation was effected three times more. 157.1g (60% of theory) of the product were obtained in 95% purity, which wasused directly for the further synthesis. NMR (CDCl₃): 7.38-7.44 (m, 4H),7.24-7.35 (m, 6H), 7.09-9.12 (m, 1H), 7.04-7.07 (m, 1H), 6.54-6.57 (m,2H, C(OH)H), 3.85-3.95 (m, 2H, OCH₂), 3.76+3.77 (2×s, 3H, OCH₃),0.83-1.69 (m, 19H).

Synthesis of2,5-bis(phenylchloromethyl)-1-(3,7-dimethyl-octyloxy)-4-methoxybenzene

In a 2 l four-neck flask with precision glass stirrer, condenser,dropping funnel, thermometer and two wash bottles (one empty, onecontaining 15% sodium hydroxide solution), 156 g (0.327 mol) of2,5-bis(phenylhydroxymethyl)-1-(3,7-dimethyloctyloxy)-4-methoxybenzenewere slurried in 600 ml of hexane and admixed with 1 ml of pyridine. Tothis was slowly added dropwise at room temperature 155.7 g (1.31 mol) ofthionyl chloride. The mixture was stirred at room temperature for 15 hand under reflux for 2.5 h. For workup, the reaction mixture was admixedat room temperature with stirring with 400 ml of saturated NaHCO₃solution and stirred over night. The phases were separated and theaqueous phase was extracted with 1×200 ml of hexane. The combinedorganic phases were washed with 1×200 ml of water and dried over Na₂SO₄.The solvent was removed under reduced pressure and the crude product waspurified by short-path distillation carried out twice (1. 140-195° C.,cooling 40° C., <10⁻³ mbar, 2. 185° C., cooling 40° C., <10⁻³ mbar). 121g (72% of theory) were obtained. NMR (CDCl₃): 7.34-7.40 (m, 4H),7.20-7.34 (m, 6H), 6.88 (s, 1H), 6.84 (s, 1H), 5.98-6.02 (m, 2H, CHCl),3.79-3.92 (m, 2H, OCH₂), 3.71 (s, 3H, OCH₃), 0.80-1.72 (m, 19H).

Example 2 Synthesis of IA2

1,4-Diformyl-2,3,5,6-tetramethylbenzene (A. P. Yakubov et al.,Tetrahedron 1993, 49, 3397) and1,4-bis(1-hydroxy-2,2-dimethylpropyl)-2,3,5,6-tetramethylbenzene (D.Casarini et a., J. Org. Chem. 1996, 61, 6240) were synthesized accordingto the literature.

Synthesis of1,4-bis(1-chloro-2,2-dimethylpropyl)-2,3,5,6-tetramethylbenzene

In a 1 l four-neck flask with mechanical stirrer, reflux condenser,dropping funnel, thermometer and two wash bottles (one empty, onecontaining 15% sodium hydroxide solution), 61.31 g (0.2 mol) of1,4-bis(1-hydroxy-2,2-dimethylpropyl)-2,3,5,6-tetramethylbenzene weresuspended in 32 g (0.41 mol, 33 ml) of pyridine and 100 ml of hexane. Tothis were slowly added dropwise with stirring 48.4 g (0.41 mol, 30 ml)of thionyl chloride, at such a rate that the internal temperature didnot exceed 50° C. The mixture was then heated under reflux for 5 h.After cooling, the reaction solution was admixed cautiously with 200 mlof ice-water with stirring. 400 ml of ethyl acetate were then added, andthe phases were separated. The aqueous phase was extracted with 2×100 mlof ethyl acetate. The combined organic phases were washed with 100 ml ofNaHCO₃ solution and with 3×100 ml of water, and dried over MgSO₄. Theproduct was purified by repeated recrystallization from ethylacetate/hexane. Yield: 20.98 g (61% of theory).

¹H NMR (CDCl₃): 0.98 (s, 18 H, tert-butyl groups), 2.35 (s, 12 H, Me),4.73 (s, 2 H, CHCl).

Example 3 Synthesis of IA3

2,5-Bis(p-trifluoromethylphenylchloromethyl)-1-(3,7-di-methyloctyloxy)-4-methoxybenzenewas synthesized in analogy to the synthesis of IA1. The purification waseffected by short-path distillation carried out twice (1. 150-215° C.,cooling 40° C., <10⁻³ mbar, 2. 191° C., cooling 40° C., <10⁻³ mbar). ¹HNMR (CDCl₃): 7.78-7.85 (m, 4H), 7.49-7.60 (m, 4H), 6.95 (s, 1H), 6.92(s, 1H), 6.02-6.06 (m, 2H, CHCl), 3.86-3.99 (m, 2H, OCH₂), 3.79 (s, 3H,OCH₃), 0.80-1.75 (m, 19H). ¹⁹F NMR (CDCl₃): −66.8 ppm (against CCl₃F asan internal standard).

This compound was synthesized in order to investigate the incorporationinto the polymer by ¹⁹F NMR spectroscopy.

Example 4 Synthesis of Typical Monomers

The synthesis of possible monomers for the polymerization according toGILCH has already been shown in the application documents WO 01/34722(EP 1232225) and WO 99/24526. The synthesis of possible monomers for thepolymerization according to the sulfinyl precursor route has beenpublished by A. J. van Bremen et al. (J. Org. Chem. 1999, 64, 3106). Atthis point, reference is therefore merely made to these documents.

The monomers used by way of example below are shown here once again forthe sake of clarity:

In these structures, C₄ is a 2-methylpropyl group, C₅ a 2-methylbutylgroup and C₈ an ^(n)octyl group.

Polymer Synthesis

In the following, the percentage molar amount of the inventive additive(IA1, IA2 and IA3) is based in each case on the total molar amount ofmonomer used.

Example 5 Synthesis of Polymer P1

Copolymer of 50% M4, 40% M1 and 10% M5 with addition of 10 mol % of IA1:

In a dry 1 l four-neck flask with mechanical Teflon stirrer, refluxcondenser, thermometer and dropping funnel, 570 ml of dry oxygen-free1,4-dioxane were heated to 99° C. A solution of 2.687 g (4 mmol) of M4,1.265 g (3.2 mmol) of M1, 0.307 g (0.8 mmol) of M5 and 0.411 g (0.8mmol) of IA1 in 30 ml of dry 1,4-dioxane was then added. A solution of2.36 g (21 mmol) of potassium tert-butoxide in 21 ml of dry 1,4-dioxanewas then added dropwise within 5 minutes to the intensively stirredmixture. This changed the color from colorless through green toyellow-green. After 5 minutes, a further 1.79 g (16 mmol) of potassiumtert-butoxide in 16 ml of dry 1,4-dioxane were added. After stirring atfrom 98 to 100° C. for 2 h, the mixture was cooled to 55° C. and amixture of 4 ml of acetic acid and 4 ml of 1,4-dioxane was added. Thenow yellow solution was poured into 850 ml of intensively stirred water.The precipitated polymer was isolated by filtration through apolypropylene filter, washed with methanol and dried under reducedpressure. The crude polymer was dissolved in 250 ml of THF at 60° C. andprecipitated by addition of 250 ml of methanol at 40° C. After dryingunder reduced pressure, this step was carried out once more. Afterdrying under reduced pressure, 1.65 g (41% of theory) of the polymer P1were obtained as bright yellow fibers.

GPC (polystyrene standard, UV detection 254 nm): M_(w)=351 k, M_(n)=73k.

A comparative polymer C1 which was synthesized under otherwise identicalconditions, but without addition of IA1, formed an insoluble gel.

Example 6 Synthesis of Polymer P2 (3)

Copolymer of 50% M1, 35% M2 and 15% M3 with addition of 10 mol % of IA2:

In a dry 3 l four-neck flask with mechanical Teflon stirrer, refluxcondenser, thermometer and dropping funnel, 1700 ml of dry oxygen-free1,4-dioxane were heated to 99° C. A solution of 5.63 g (14.25 mmol) ofM1, 4.24 g (9.98 mmol) of M2, 1.32 g (4.28 mmol) of M3 and 0.98 g (2.85mmol) of IA2 in 25 ml of dry 1,4-dioxane was then added. A solution of8.30 g (74 mmol) of potassium tert-butoxide in 74 ml of dry 1,4-dioxanewas then added dropwise within 5 minutes to the intensively stirredmixture. This changed the color from colorless through yellow toyellow-orange. After 5 minutes, a further 7.7 g (68.5 mmol) of potassiumtert-butoxide in 70 ml of dry 1,4-dioxane were added. After stirring atfrom 98 to 100° C. for 2 h, the mixture was cooled to 50° C. and amixture of 17 ml of acetic acid and 18 ml of 1,4-dioxane was added. Thenow orange solution was poured into 1900 ml of intensively stirredwater. The precipitated polymer was isolated by filtration through apolypropylene filter, washed with methanol and dried under reducedpressure. The crude polymer was dissolved in 750 ml of THF at 60° C. andprecipitated by addition of 750 ml of methanol at 40° C. After washingwith methanol and drying under reduced pressure, this step was carriedout once more with 500 ml of THF and 500 ml of methanol. After dryingunder reduced pressure, 3.40 g (43% of theory) of the polymer P2 (3)were obtained as yellow-orange fibers.

GPC (polystyrene standard, UV detection 254 nm): M_(w)=579 k, M_(n)=145k.

A comparative polymer C2 which was synthesized under otherwise identicalconditions without inventive additive IA2 had an M_(w)=1120 k and anM_(n)=342 k.

Example 7 Synthesis of Polymer P3

Homopolymer composed of 100% M6 with addition of 10 mol % of IA1:

In a dry 500 ml four-neck flask with mechanical Teflon stirrer,thermometer and dropping funnel, a solution of 6.0 g (20 mmol) of M6 and1.03 g (2 mmol) of IA1 in 140 ml of dry THF was degassed at 30° C. for 1h by passing a nitrogen stream through the solution. To this was added adegassed solution of 2.36 g (21 mmol) of potassium tert-butoxide in 60ml of dry oxygen-free THF in one portion, and the mixture was stirred at30° C. for 1 h. The reaction mixture was then poured into 1000 ml ofvigorously stirred ice-water and the precipitated polymer was isolatedby filtration through a polypropylene filter, washed with methanol anddried under reduced pressure. The crude polymer was dissolved at 60° C.in 500 ml of THF, precipitated by addition to 750 ml of methanol,filtered and dried. This step was repeated once more. After drying underreduced pressure, 3.61 g (58% of theory) of the polymer P3 were obtainedas colorless fibers.

GPC (polystyrene standard, UV detection 254 nm): M_(w)=483 k, M_(n)=173k.

A comparative polymer C3 which was synthesized under otherwise identicalconditions but without inventive additive IA3 had an M_(w)=812 k and anM_(n)=253 k.

The thermal conversion of these polymers unsubstituted on the aryl unitto poly(arylenevinylenes) leads to insoluble polymers. This conversionhere was therefore not carried out in solution.

Example 8 Synthesis of Polymer P4

Copolymer of 50% M4, 40% M1 and 10% M5 with addition of 10 mol % of IA3:

The synthesis of P4 was carried out in analogy to P1, except that theadditive IA3 (0.518 g, 0.8 mmol) was used here in order to investigateits incorporation into the polymer by ¹⁹F NMR spectroscopy. Noelectroluminescence analyses thereof were carried out. For this polymer,a molecular weight of M_(w)=382 k and M_(n)=84 k was determined by GPCwith internal polystyrene standard.

For ¹⁹F NMR spectroscopy analysis, 5 mg of the polymer P4 with additionof 1.5-10⁻³ mg (1.03·10⁻⁵ mol) of trifluorotoluene as a quantitativereference were dissolved in 0.8 ml of CDCl₃, and the ¹⁹F NMR spectrumwas recorded. The signal of trifluorotoluene was calibrated to −63.9ppm. The ¹⁹F signal of the polymer was detected as a broadened signal at−64.5 to −66 ppm. By integration over the fluorine signal of the polymerand of the reference substance, a fluorine content of the polymer ofapprox. 34 ppm was determined. From this, it can be determined that theadditive IA3 is also incorporated into the polymer chain and does notonly constitute the end groups of the polymer. Were IA3 only toconstitute the end groups, a fluorine content of approx. 11 ppm would beexpected.

Just as described for polymer P1, P2 (3), P3 and P4, further polymerswere synthesized with the process according to the invention andcomparative polymers with conventional processes. The polymers arecompiled in Table 1 together with the results of the GPC determinationof the molecular weight, viscosity data and characterization of theelectroluminescence (where possible).

TABLE 1 Polymer M1^([a]) M2^([a]) M3^([a]) M4^([a]) M5^([a]) M6^([a])IA1^([b]) IA2^([b]) Comment M_(n) ^([c]) M_(w) ^([c]) Viscosity^([d])Max. eff.^([e]) LD^([f]) λ_(max) ^([g]) P1 40 50 10 10  73k 351k 2.213.8 460 518 C1 40 50 10 gelled P2(1a) 50 35 15 2.5 214k 947k 10.2 11.11050 545 P2(1b) 50 35 15 2.5 210k 968k 10.1 11.2 1070 544 P2(1c) 50 3515 2.5 209k 961k 10.0 11.3 985 545 P2(2) 50 35 15 5 159k 778k 5.7 11.11100 544 P2(3) 50 35 15 10 145k 579k 2.7 10.9 785 545 P2(4) 50 35 15 15122k 428k 1.7 10.8 820 546 C2 50 35 15 342k 1120k  22 11.5 1000 544 P3100 10  173k^([h])  483k^([h]) n.a. n.a. n.a. C3 100  253k^([h]) 812k^([h]) n.a. n.a. n.a. P4(1) 25 60 15 5 200k 887k 6.9 10.5 2200 551P4(2) 25 60 15 10  95k 563k 3.0 10.2 2000 553 C4 25 60 15 gelled P5(1)40 30 30 5 201k 822k 9.1 15.6 621 513 P5(2) 40 30 30 10 156k 586k 4.613.8 523 513 C5 40 30 30 gelled n.a. n.a. n.a. ^([a])Data in percentbased on the overall composition of the polymer without taking intoaccount the inventive additive. ^([b])Amount of the inventive additivein percent based on the total amount of monomer. ^([c])in g/mol;determined by GPC (THF; column set SDV500, SDV1000, SDV10 000 (from PSS)35° C., UV detection 254 nm, polystyrene standard). ^([d])in mPas; 0.5%solution in toluene, 40 s⁻¹. ^([e])Maximum efficiency in cd/A, for theproduction of the PLEDs see Example 9. ^([f])Lifetime up to decline inthe starting brightness to 80%; measurement at room temperature and astarting brightness of 1000 cd/m²; start of measurement 1 h after startof current flow; for the production of the PLEDs Example 9.^([g])Maximum of the emission (electroluminescence) in nm.^([h])Molecular weight based on the precursor polymer.

From the comparison of the example polymers P with the comparativepolymers C, it is readily discernible that the molecular weight and thusthe solubility of the polymers and viscosity of the polymer solutions isinfluenced very strongly by the selected process. Specifically polymerswhich have been synthesized by prior art processes frequently have toohigh a molecular weight for many applications or are found to beunprocessible or insoluble in the sense of this text.

The entries in Table 1 demonstrate that the process according to theinvention has excellent suitability for molecular weight control in thesynthesis of poly(arylenevinylenes). At the same time, the properties ofthe polymers on use in PLEDs (efficiency, lifetime) are not influenced.Furthermore, the process according to the invention significantlyimproves the reproducibility, as can be seen readily by the results forpolymer P2(1a)-(1c).

Example 9 Production and Characterization of LEDs

LEDs were produced by the general process outlined below. This had to beadapted in the individual case to the particular circumstances (forexample solution viscosity and optimal layer thickness of the compoundin the device). The LEDs described below were in each case two-layersystems, i.e. substrate//ITO//PEDOT//polymer//cathode. PEDOT is apolythiophene derivative.

General Process for Producing High-Efficiency, Long-Lifetime LEDs:

After the ITO-coated substrates (for example glass supports, PET films)have been cut to the correct size, they are cleaned in an ultrasoundbath in several cleaning steps (for example soap solution, Milliporewater, isopropanol).

For drying, they are blown with an N₂ gun and stored in a desiccator.Before they are coated with the poly(arylenevinylenes), they are treatedwith an ozone plasma unit for approx. 20 minutes. A solution of theparticular poly(arylenevinylenes) (generally having a concentration of4-25 mg/ml in, for example, toluene, chlorobenzene, xylene:cyclohexanone (4:1)) is prepared and dissolved at room temperature bystirring. Depending on the compound, it may also be advantageous to stirat 50-70° C. for a certain time. When the compound has dissolved fully,it is filtered through a 5 μm filter and applied by spincoating with aspincoater at variable speeds (400-6000). It is thus possible to varythe layer thicknesses in the range of from approx. 50 to 300 nm.Beforehand, a conductive polymer, preferably doped PEDOT or PANI, isusually applied to the (structured) ITO. Electrodes are also applied tothe thus obtained polymer films. This is generally effected by thermalvapor deposition (Balzer BA360 or Pfeiffer PL S 500). Subsequently, thetransparent ITO electrode is contacted as the anode and the metalelectrode (for example Ba, Yb, Ca) as the cathode, and the deviceparameters are determined.

The results which have been obtained with poly(arylenevinylenes) whichhave been synthesized by the process according to the invention arecompiled in Table 1.

1. A process for preparing poly(arylenevinylenes) frombis(halomethyl)arylene of the formula (XXVI),

which comprises base-induced dehydrohalogenation, wherein the reactionis carried out in the presence of between 2 and 40 mol% of one or morecompounds of the formula (I):

where the symbols are defined as follows: Aryl is the same or differentat each instance and is a bivalent aromatic or heteroaromatic ringsystem which has from 2 to 40 carbon atoms and is substituted by R¹radicals, or an R¹-substituted or unsubstituted stilbenylene unit; thetwo substituents CHXR and CHYR are arranged in such a way that there isan even number of aromatic atoms between them; the aryl and heteroarylsystems may also be part of a larger fused aromatic ring system; thepossible substituents R¹ may potentially be situated at any freeposition; R is the same or different at each instance and is an alkylchain which has from 4 to 40 carbon atoms, and may also be substitutedby one or more R¹ radicals or be unsubstituted, in which one or morenonadjacent carbon atoms may also be replaced by —CR²═CR²—, —C≡C—,—NR²—, —O—, —S—, —CO—, —CO—O—, —CONR²—, —O—CO—O—, and one or morehydrogen atoms may also be replaced by fluorine, an aromatic orheteroaromatic ring system which has from 2 to 40 carbon atoms and maybe substituted by R¹ or be unsubstituted, an R¹-substituted orunsubstituted stilbenyl or tolanyl unit, —Si(R²)₃, —N(R²)₂, —OR² or acombination of these systems; the aryl and heteroaryl systems may alsobe part of a larger fused aromatic ring system; the possiblesubstituents may potentially be situated at any free position; X is thesame or different at each instance and is Cl, Br, I,trifluoromethanesulfonate or arylsulfonate; Y is the same or differentat each instance and is Cl, Br, I, trifluoromethanesulfonate,arylsulfonate or R¹; Z is the same or different at each instance and isCl, Br, I, trifluoromethanesulfonate, arylsulfonate or —S(O)R²; R¹ isthe same or different at each instance and is a straight-chain, branchedor cyclic alkyl chain having from 1 to 40 carbon atoms, in which one ormore nonadjacent carbon atoms may also be replaced by —CR²═CR²—, —C≡C—,—NR²—, —O—, —S—, —CO—, —CO—O—, —CONR²—, —O—CO—O—, and one or morehydrogen atoms may be replaced by fluorine, an aromatic orheteroaromatic ring system which has from 2 to 40 carbon atoms and mayalso be substituted by one or more nonaromatic R¹ radicals, asubstituted or unsubstituted vinyl group or Cl, F, CN, N(R²)₂, B(R²)₂;the aryl and heteroaryl systems may also be part of a larger fusedaromatic ring system; the possible substituents may potentially besituated at any free position; two or more R¹ radicals together may alsoform a ring system; R² is the same or different at each instance and isH, a straight-chain, branched or cyclic alkyl chain having 1 to 22carbon atoms, in which one or more nonadjacent carbon atoms may also bereplaced by —O—, —S—, —CO—O—, —O—CO—O—, and one or more hydrogen atomsmay also be replaced by fluorine, an aryl or heteroaryl system which hasfrom 2 to 40 carbon atoms and may also be substituted by one or morenonaromatic R¹.
 2. The process as claimed in claim 1, wherein thehalogen atoms in the bis(halomethyl)arylene monomers are the same ordifferent and are each Cl, Br or I.
 3. The process as claimed in claim1, wherein the polymerization is carried out in an ether, an aromatichydrocarbon, a chlorinated aromatic compound or a mixture of thesesolvents.
 4. The process as claimed in claim 1, wherein the reaction iscarried out in a concentration range from 0.005 to 5 mol/L(monomer/solution volume).
 5. The process as claimed in claim 1, whereinthe bases used are alkali metal hydroxides, alkali metal alkoxides ororganic amines or amides, or else alkali metal hydrides or metalorganyls, provided that the solvents used are not DMSO, alcohols orchlorinated solvents.
 6. The process as claimed in claim 1, wherein theamount of the base used is in the range from 2 to 10 equivalents (basedon one equivalent of monomer).
 7. The process as claimed in claim 1,wherein for the compound of the formula (I): Aryl is the same ordifferent at each instance and is a bivalent aromatic ring system whichhas from 2 to 40 carbon atoms and is substituted by up to 4 substituentsR¹, or an R¹-substituted or unsubstituted stilbenylene unit; the twosubstituents CHXR and CHYR are arranged in such a way that there is aneven number of aromatic atoms between them; the aryl system optionallyis part of a larger fused aromatic ring system; the possiblesubstituents R¹ may potentially be situated at any free position; and Xis the same or different at each instance and is Cl, Br, I.
 8. Theprocess as claimed in claim 7, wherein the compound of the formula (I)is selected from the formulae (II) to (XXV) which may be substituted orunsubstituted: